Liquid mixer and method of mixing



1954 G. c. GESTER, JR, ET AL 2,669,438

LIQUID MIXER AND METHOD OF MIXING Filed March 8, 1951 SLUDGE 2; [I g g 1 a Y 5% 9 INVENTORS GEORGE C. GESTER JR. DONALD E. SEWELL ATTORNEYS REACTION ZONE Patented Feb. 16, 1954 UNITED STATES PATENT OFFICE LIQUID MIXER AND METHOD OF MIXING corporation of Delaware Application March 8, 1951, $crial No. 214,554

6 Claims.

This invention relates to liquid mixers and methods of mixing and particularly refers to those in which two liquids of widely different characteristics are introduced into a confined housing and are distributed and agitated in such a manner that one liquid is finely divided and uniformly distributed throughout the other.

In the chemical treatment of liquids, for example certain petroleum distillatee, with reagents such as sulfuric acid which are immiscible therewith, it is sometimes desirable that the reagent should be uniformly and finely dispersed throughout the oil, in very small drops, and that the mixture thus formed be quickly removed from the zone of agitation and mixing to what we term a reaction zone. in which the mixture is relatively quiescent, after which the reacted materials may be separated in any desired manner to remove acid reaction products, sludge, and the like from the treated oil. The differences in physical properties, such as viscosity, surface tension, and specific gravity of the liquids to be mixed renders this a somewhat difficult problem. Various arrangements of circular impellers, with and with out serrations, notches, vanes, etc. have been prepared to be placed in circular housing of Varied configurations and rotated to disperse and mix the bulk of the two or more liquids which are to be contacted. For a given degree of mixing these involve the expenditure of relatively large amounts of energy, most of which is spent in churning the bulk liquids which raises their temperature is wasteful of power.

This invention comprehends broadly a method and means for mixing two liquids, for example oil and sulfuric acid, involving the formation of separate thin films of the liquids, for example by spreading them on opposite sides of a smooth, rapidly rotating disc. and. merging the films in a laterally confined circular chamber, from which the resultant fine dispersion of acid in the oil may be removed quickly to a relatively quiescent reaction zone, after which the reaction products, oil, acid sludge, etc, may be separated by gravity, by centrifugal means, electrical means or any others that may be suitable. Desirably, but not necessarily, the merging thin films are subsequently agitated or broken up by means such as thin blades rotating substantially in the merging plane, and if desired these blades may be integral with or extensions of the disc on which the films are initially formed.

"It has been found that, by utilizing this invention in lubricating oil processing, the greatest quantity of desired primary reaction products are formed between the initial surface of the acid droplets and the untreated oil external to them, with aminimum of undesired secondary reaction between the unreacted acid at the center of the acid droplets and the primary reaction product layer just described. if these secondary reaction products are released from the composite droplets to enter the external oil phase, their presence therein has been found to be quite detrimental to the quality of the finished product. The cause of such release is generally long-continued or uncontrolled agitation, particularly in the case of bulk mixers, which continue to beat or to churn the mixture of unreacted oil and the composite droplets of acid surrounded by the desired primary reaction product layer. Another cause of secondary reaction products release to the ex, ternal oil phase is long-continued or uncone trolled time of contact between the composite droplets and the external phase after the 60111131 3.- tion of the initial dispersion of the acid through? out the untreated oil. In addition to the advantages just described, the invention herein has been found to accomplish the required contact of the immiscible liquids with a minimum of mechanical energy input.

It is an object of this invention to provide a method of rapidly and completely dispersing one liquid within another liquid that is immiscible therewith.

Another object is to provide an improved method of dispersing a reagent liquid, such as sulfuric acid, within a liquid of dissimilar properie such as a lubricating oil distillate, so th t a subsequent chemical reaction between the two may be completed under controlled conditions to obtain a desired purifying or modifying action of the second liquid.

Another object is to provide a method of mixing an aqueous liquid within non-aqueous liquid in very droplets. to give a maximum surface area to the dispersed phase aqueous droplets which are in reactive contact with the continuous phase non-aqueous liquid with a minimum of volume of said droplets.

Another object is to provide an improved mixer of simple and compact form and which will handle relatively large quantities of liquids with a minimum of power input.

These and other objects and advantages of the invention will be further apparent from the following description of a preferred form of the ap nomtus and the method of mixing embodied therein, taken in connection with the attached 3 drawing, which forms a part of this specification.

In the drawing,

Fig. 1 is a vertical sectional view taken in a plane at right angles to the plane of mixing;

Fig. 2 is a side elevational view on line 2-2 of Fig. 1, and illustrates one form of the rotor disc;

Fig. 3 is a side elevational view on line 3-3 of Fig. 1 and illustrates a preferred form of liquidcollecting and liquid-controlling means;

Fig. 4 is a schematic fiow diagram of the method as applied to a sulfuric acid-lubricating oil distillate treating process.

Referring to the drawing, and particularly to Fig. 1, reference numeral I designates generally the housing of the mixer, in this example comprising a back plate II of suitable acid-resisting metal, such as a silicon-iron alloy, provided with a shallow recess I2 in one face. A first liquid inlet connection I3 in plate II conveys liquid to a system of distributor passages Id communicating with recess I2 near its center. A rotor generally designated I5, also of suitable acid-resistant metal, is mounted upon shaft It which rotates in bore I'I', sealed against leakage by packing gland I8 and is driven by any suitable power source (not shown) at relatively high speed, 1,000 to 15,000 R. P. M. The clearance between the bottom of recess I2 and the back face of rotor I is desirably small to provide a confined space for a purpose to be explained in more detail below.

The rotor I5 itself is formed with a generally disc-shaped center portion I0 and, in this example, has tapered and diametrically opposed blade portions 20 merging tangentially with and of substantially the same thickness as the center, the tips of the blade portions extending substantially to the outer diameter of recess I2. Desirably, both the disc-shaped center portion I9 and the blade portions 20 are provided with smoothly tapered or knife-like edges as at 2I.

The cover plate 22 which complete the mixer housing I0 is of similar material to that of back plate II and is secured to the latter by means such as circumferentially spaced through-bolts I 23. Plate 22 is also slightly recessed as at 24 and this recess may be provided with radial vanes 25. An inlet connection 20 for the second liquid is provided in the center of plate 22 and terminates in a restricted nozzle 2'1 which directs the second liquid onto the center of the disc-shaped portion IQ of rotor I5 to form a uniform, outwardly flowing, thin film thereon. Vanes 25 may assist in the uniformity of this flow by preventing the outwardly-flowing film from swirling due to rotation of rotor 15 in the confined space within the housing if The outer edge of recess 24 in cover plate 22 is deepened as at 28 to form an annular mixturecollecting chamber from which the mixed liquids leave the housing It! through outlet connection 29. In this example, annulus 28 is substantially entirely within cover plate 22 and at one side of rotor I5, for a purpose to be explained below, but, if desired, it may be formed partly inback plate I I to be symmetrically disposed with respect to the plane of rotor I5.

In operation, the first liquid, in this example a lubricating oil distillate, is introduced into the housing I0 through connection I3 and is distributed by passages I4 to form a thin, outwardly moving film on the back face of the disc-shaped center portion I9 of rotor I5. At the same time the second fluid, in thiscase concentrated sulf-uric acid, is introduced into housin g I0 tl rouglr inlet 26 and is directed by nozzle 21 to form a thin, outwardly moving film on the front face of the disc-shaped center portion of rotor I 5. As the two liquid films thus formed pass over the tapered knife-like edges 2| of rotor I5, they merge intimately, and immediately thereafter are violently sliced or sheared by the larger diameter blade portions 20. In the arrangement shown, with the annular mixture-collecting chamber 28 entirely on the acid side of the rotor blade tips, it will be obvious that, before any of the first liquid (oil) entering the housing II through inlet I3 can leave the housing through outlet 29, it will have to pass through the merging plane swept by blades of the rapidly revolving rotor I5. To facilitate this, rotor I5 may be driven in the direction shown by the arrow, Fig. 2, which is opposite to the direction of the final liquid mixture through the tangential outlet 29 from annulus 28. In practice, with a mixer for an oil throughput of about 100 barrels/hour, having a 6-12 inch diameter rotor, the speed of rotation would range from 1,000 to 6,000 R. P. M., giving blade tip velocities of about to 320 feet per second, at a power input, depending upon the speed, of only about 30 H. P. With smaller sizes, speeds up to 15,000 R. P. M. have been found desirable.

Referring now to the fiow diagram of Fig. 4, reference numeral 3I designates the lubricating distillate or oil supply tank, from which the oil passes through conduit 32 and pump 33 to inlet I3 of mixer Ill. Acid is stored in tank 34 from which a fluid pressure source 35 forces it through conduit 36 to inlet 26 of mixer III, the latter being driven by motor 31. Ratios of acid to oil may range from 0.1 to 10 lbs. of acid to one gallon of oil. By suitable choice of proportions of the mixer, conduits and flow control means which are well known, it can be arranged that, immediately after the mixing operation the mixture is passed through outlet conduit 38 to a relatively quiescent reaction zone 39 to remain in contact for the desired period of time. At the end of this time interval, which is controlled by the fiow rate and the volume of zone 39, the reacted mixture passes through conduit 40 to separator 4!, which may be of a simple gravity type, or may be a centrifugal or electrostatic separator. From the separator 4| the treated oil may be removed from the system through conduit 43 and the waste products, sludge, etc., may be removed from the system through conduit 44. Alternatively, the mixture may pass directly from mixer IIl through bypass 42 to separator 4|, without passing through or remaining in reaction zone 39.

In conclusion, it will be appreciated that a method and means for mixing two liquids, which may be dissimilar in their several physical and chemical properties, have been described and illustrated. It is believed that the essential features of the invention reside in the formation of separate, rotating, outwardly moving films of the liquids which are smoothly merged in a plane in a confined space, and are thereafter sliced or sheared to form a fine suspension or dispersion of one liquid in the other, after which the mixture may be rapidly removed from the mixing zone to a relatively quiescent zone where the desired reaction, as in the case of acid and oil, may continue to take place for the optimum length of time.

Although a specific arrangement and mode of,

operation have been described and illustrated,

it is obvious that numerous changes could'bemade without departing from the essential tea;

tures of the invention, and all those that fall within the scope of the appended claims are considered to be embraced thereby.

We claim:

1. A method of mixing dissimilar liquids comprising the steps of forming separate rotating plane films of said liquids, merging said films in a plane and flowing the merged films radially outwardly in a confined path into a mixing zone to form an intimate dispersion of one liquid in the other liquid.

2. A method according to claim 1, with the added step of mechanically shearing the merged film in the plane of their merging.

3. A method of treating oil with a liquid reagent that is immiscible therewith comprising the steps of forming separate rotating plane films of said oil and said reagent, merging said films in a confined path to form an intimate dispersion of the reagent liquid in said oil and removing the mixture into a reaction zone.

4. A method according to claim 3 with the added step of mechanically shearing the merged films in the plane of their merging.

5. Mixing apparatus for liquids comprising a housing defining a confined flat circular chamher, a smooth-faced disc-shaped rotor rotatable in said chamber, the periphery of said rotor being tapered inwardly from each face to a knife edge, a plurality of passages in said housing for admitting liquids to said confined chamber to direct them against substantially the center of said rotor and on opposite sides thereof to form outwardly- 6 moving uniform liquid films thereon which smoothly merge in a single plane in said cham-- ber, and a liquid outlet from the periphery of said chamber.

6. Mixing apparatus according to claim 5, in which said rotor is provided with radially directed blade portions of the same thickness as said rotor and merging tangentially with the central disc portion thereof, said blade portions extending substantially throughout the diameter of said chamber.

GEORGE C. GESTER, JR. DONALD B. SEWELL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 228,321 Cornwall et al June 1, 1880 1,587,063 Austin June 1, 1926 1,819,118 Preleuthner Aug. 18, 1931 2,077,226 De Bethune Apr. 13, 1937 2,086,338 Scdergreen July 6, 19 7 2,109,501 Osius Mar. 1, 1938 2,240,213 Fromm Apr. 29, 1941 2,272,573 Messmore Feb. 10, 1942 2,287,067 Schmidt June 23, 1942 FOREIGN PATENTS Number Country Date 782,025 France May 27, 1935 876,314 France Nov. 3, 1942 

